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  <title>Document</title>
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<body>
  <div id="app">
    <a href="#/home">home</a>
    <a href="#/about">about</a>
    <div class="content">Default</div>
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    window.addEventListener("hashchange", () => {
      switch (location.hash) {
        case "#/home":
          contentEL.innerHTML = "Home";
          break;
        case "#/about":
          contentEL.innerHTML = "About";
          break;
        default:
          contentEL.innerHTML = "Default"
      }
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